Patent GB-1533718-A (GB)
Title: Assembly for dehydrating air to be supplied to blast furnace
IPC: C21B9/16
Filed: 1976-08-09
Abstract: 1533718 Dehydrating air for blast furnaces TAKASAGO THERMAL ENG CO Ltd and NIPPON STEEL CORP 9 Aug 1976 33132/76 Heading B1L [Also in Divisions C7 F2 and F4] An assembly for drying atmospheric air to be supplied to a blast furnace comprises a casing 14 subdivided by a partition 28 into a regenerating zone 29 and a drying zone 30, at least one rotor 15 impregnated with a regenerative hygroscopic substance and rotatably mounted so as to radially extend across cross-sections of both zones 29, 30, a precooler 16 in zone 30 upstream of the rotor(s) 15, a relative humidity regulator 18 between pre-cooler 16 and the rotor(s) 15, an aftercooler in zone 30 downstream of the rotor(s), and conduits for circulating a heat transfer medium through the regulator and through the after-cooler in series so as to effect heat transfer between the two. The pre-cooler 16 partially dehydrates the air flow, and the after-cooler transfers heat via the heat transfer medium to the regulator 18 to lower the relative humidity of air leaving the pre-cooler 16. It is stated that deliquescence of the hygroscopic substance in the rotor(s) 15 is thus avoided. In the form shown, two aftercoolers 17, 31 are provided. A pump 39 circulates water in a closed circuit including regulator 18 and after-cooler 31. A pump 41 supplies pre-cooler 16 with cooled water from a refrigerating unit R, and water from a cooling tower 42 is supplied to the unit R and the after-cooler 17 by pumps 44, 43 respectively. Each of the components 16, 17, 18, 31 is a finned tube heat exchanger (Fig. 5). In another embodiment (Fig. 4), the aftercooler 31 is omitted and water from cooling tower 42 is passed through the after-cooler 17 and then through the regulator 18. Two rotors 15 may be arranged between two plates 48 having apertures 56. The rotors are driven by motors 47, 47' via endless belts 46, 46'. Peripheral seals are provided between the peripheries of the rotors and the edges of apertures 56. A clearance between each face of each rotor and the adjacent portion of the partition 28 is sealed by a packing element which abuts at its ends the edge of the corresponding aperture 56 and has arms 52 and 53 which contact the adjacent rotor flat surface to define a substantially sealed space 57. A tube 58 provides communication between the space 57 and the lower pressure region of zone 29 downstream of the rotors, to substantially prevent leakage of hot gas in zone 29 into the air flow in zone 30. Each rotor 15 comprises two honeycomb structure asbestos discs bonded together, the upstream disc carrying activated carbon as zeolite to absorb gaseous impurities, and the downstream disc being impregnated with lithium chloride. Dried air from the assembly is passed by a blower (12, Fig. 1) to a blast furnace via hot air furnaces (11). Waste gas from the blast furnace is passed through a scrubber, a cooling drier (4) including a coarse filter (20), a cooler (19) supplied with cooled water and a droplet eliminator (21), through a gas cleaner (5) including a layer (23) of activated carbon and a HEPA filter (24) to a gas burner (6) having a propane pilot burner. The combustion products from the burner (6) are drawn through the regenerating zone 29 of the drying assembly by blowers 34, 34'.